1. Field of the Invention
This invention relates to a photosensitive composition and, more particularly, it relates to a stabilized photosensitive composition which when exposed to actinic radiation produces visible contrast between exposed and unexposed areas.
2. Description of the Prior Art
In many photographic applications such as, for example, lithography, photoresists, etc., it is preferred that after image-exposure, the exposed portions are visibly distinguishable from the unexposed portions. A particularly effective method for obtaining this effect is to incorporate various leuco compounds which are oxidized into the corresponding dyes using various organic polyhalogen compounds or photooxidizing agents (see, e.g., Phot. Sci. Eng., 5, 98-104 (1961) and U.S. Pat. No. 3,042,515).
Since the composition comprising such a leuco dye and a photooxidizing agent discolors when it is exposed to air or oxygen, an antioxidant is incorporated into the composition. For example, U.S. Pat. No. 3,042,515 discloses a method for preventing discoloration of leuco dyes when they are exposed to air or oxygen in the presence of light and/or heat by the addition of an organic reducing agent having a hydroxy group on a benzene ring and also at least a hydroxy group or an amino group at another position of the benzene ring (e.g., hydroquinone, catechol, resorcinol, hydroxyhydroquinone, phlorglucinol, and aminophenols such as o-aminophenol and p-aminophenol). Also, U.S. Pat. No. 4,066,459 discloses that a stable printing out composition containing a leuco dye and a photooxidizing agent showing less discoloration during the storage thereof is obtained by adding thereto an antioxidant. However, even when these compositions are stored for a long period of time or under high temperature and high humidity conditions, they discolor and hence further improvement has been desired.